48 Cards in this Set
| Front | Back |
|---|---|
|
mosaic evolution
|
a pattern of evolution in which different features evolve at different times, both within and between species
ex: ancestral (apelike) and derived (bipedalism) are mixed.
ex: dental, loco, and neurological evolved at different rates
|
|
hominin distinguishingcharacteristics
|
loco: biped.
brain: increased brain size
dentition
tool making behavior: increased trend of cultural dependency in later hominids
culture
|
|
paleoanthropology
|
the study of ancient human evolution through fossil records
|
|
multidisciplinary of paleoanthropology
|
seeking to construct every possible bit of information concerning the dating, anatomy, behavior, and ecology of our hominin ancestors; pertains to research from other scientific fields or disciplines
|
|
taphonomy
|
the study of burial or deposition of bones/ fossils through things like:
water action
carnivore, rodent, human influence
physical and chemical disintegration
|
|
Olduvai Gorge
|
in the Great Rift Valley, is one of the most important paleoanthropological sites in the world and has been instrumental in furthering the understanding of early human evolution. 2000 years ago it was a small lake surrounded by grassland and marsh landscape w/in a large basin or depressio…
|
|
Relative Dating
|
tells us that something is older or younger than something else but not by how much.
|
|
stratigraphy
|
a method of relative dating
study of the sequential layering of deposits
based on the principle of superposition: a lower stratum (layer) is older than a higher stratum.
|
|
fluorine dating
|
method of relative dating (applies only to bones)
bones in the earth are exposed to the seepage of groundwater which contains fluorine.
the longer a bone lies in the earth, the more fluorine it will contain.
|
|
chronometric (absolute) dating
|
gives an estimate in actual number of years
certain radioactive isotopes of elements are unstable, causing them to decay and form an isotopic variation of another element
since the rate of decay follows a definite mathematical pattern, the radioactive material forms an accurate geologi…
|
|
K/Ar
|
the amount of a radioactive isotope is converted chemically to a daughter product.
Potassium-40 (K): half-life of 1.25 billion years and produces argon-40 (Ar).
used in dating materials in the 1-5 million year range
used to study volcanic ash ages
|
|
C14
|
carbon-14: half-life of 5,730 years
used to measure the age of organic materials (such as wood, bone, cloth, and plant remains).
used to study the latter stages of hominid evolution.
living, you inhale and consume carbon-14. when dead, your proportion of carbon-12 increases and carbon…
|
|
hominid origins
|
the earliest fossils identifiable as hominids are all from Africa, 6-4 million years ago
|
|
bipedal adaptation
|
primary form of loco seen only in hominins.
bipedalism is a major anatomical innovation. It involves the reorganization of several anatomical regions:
pelvis
femur
vertebrae
foot
skull base
|
|
bipedal adaptation (theories of)
|
while still in trees, our primate ancestors were adapted to a fair amount of upper body erectness.
some believe that maybe natural selection favored those who came to the ground to forage for food on the forest floor.
|
|
bipedal adaptation (features of)
|
carry heavy objects
run faster/ farther
less solar radiation
more wind on surface areas
loss of body hair and gain sweat glands
|
|
habitual bipedalism
|
bipedal locomotion as the form of loco shown by hominins most of the time.
most efficient
|
|
obligate bipedalism
|
bipedalism as the ONLY form of locomotion.
other modes of loco became impossible because of anatomical changes.
|
|
early human ancestors found in...
|
pliocene
(savanna grasslands)
|
|
cranial capacity
|
a measure of the volume of the interior of the cranium (braincase (head size)) of those vertebrates who have both a cranium and a brain
(basically, depending how big your head is, that is how big your brain is too).
|
|
early hominins (pre-australopitchecines)
|
represented by a discovered cranium
small, no larger than a modern chimp's, but massively built with huge brow ridges in front, crest on top, and large muscle attachments in the rear.
lack of a shearing canine/ premolar arrangement: honing complex.
|
|
early hominins (pre-australopitchecines) cont...
|
-6-4.4 mya
-combination of primitive and derived traits.
-found in east africa
-sahelanthropus
-orrorin
-ardipithecus ("ardi")
|
|
sahelanthropus
|
7 mya
From Chad
discovered cranium
ape-like AND hominin features
flat face
reduced canines
thick brow ridge, skull flattens out behind it
position of foramen magnum is between that of a quadrapedal ape and that of a bipedal hominin.
|
|
Orrorin
|
6 mya, Tugen Hills
best evidence as earliest hominin
top part and angle of femur (thick) demonstrates bipedalism
|
|
Ardipithecus
|
late miocene (earlier than 5 mya)
Middle Awash, Ethiopia
toe bone (divergent) show it was a well-adapted biped.
length of arms in comparison to legs
short or broad pelvis
|
|
Australopithecines: gracile and robust
|
gracile: slender and lean
robust: thick, big muscles
|
|
australopithecines
|
diverse forms, some more primitive, others highly derived (4.2-1.2 mya)
all clearly bipedal
all have relatively small brains
|
|
A. Afarensis
|
Hadar, Ethiopia
ape-like (small brain and prognathism)
bipedal (knee joint and fossil footprints)
3.9-3.7 mya
|
|
A. Afarensis (Lucy)
|
almost 40% of a skeleton: one of the most complete individuals from anywhere in the world for the entire period before about 100,000 years ago.
|
|
Laetoli, Tanzania
|
3.7-2.5 mya
footprints of australopithecines and a. afarensis found by Mary Leaky
footprints show bipedalism
|
|
Laetoli trail
|
a trail of hominid footprints dating 3.6 mya
showed they were bipeds
showed they moved in a slower fashion, with a short stride
|
|
facial prognathism
|
found in a. afarensis
forward thrust of the jaw in relation to the rest of the skull
apes have this, humans do not
|
|
non-divergent big toe
|
found in a. afarensis
forward facing
walks as a human
non-opposable/grasping
|
|
A. africanus
|
south africa
gracile
small brained
shorter arms than Lucy (afarensis)
"Taung child"
2.5 mya
infant specimen
|
|
A. robustus
|
south africa
like Lucy from the neck down
|
|
taung baby
|
5/6 year old child fossil found in South Africa
|
|
A. boisei
|
australopithecus species
hyper-robust
2.5-1 mya
East Africa
Olduvai Gorge, Tanzania
Lake Turkana, Kenya
|
|
A. aethiopicus
|
East Africa, Ethiopia 2.5 mya
"black skull"
robust features but smaller brain (400 cc)
large teeth, large muscle attachments, large face
sagittal crest
brow ridges
thick cheek bones
|
|
Australopithecine evolutionary trends
|
powerful mastication
sagittal/nuchal crests
temporalis muscle
post-orbital constriction
ape-sized cranial capacity
|
|
powerful mastication
|
develop a mouth for more powerful chewing
back teeth get bigger, front teeth get smaller
jaws get bigger and wider, face changes into more vertical.
|
|
Sagittal crests/ nuchal crests
|
sag- crest in middle of skull that allowed more space for chewing muscles
nuchal- where neck muscles attach to skull
|
|
temporalis muscle
|
under cheekbones
elevates mandible
|
|
masseter muscle
|
closes jaw for chewing
prime mover
|
|
post-orbital constriction
|
room for temporalis muscle
|
|
A. sediba
|
transitional species from Austra to Homo.
mix and match of both ape and human like traits
precision grip (tool- making).
|
|
secondary altriciality
|
1. "Premature" relative to other primates, unusually dependent infants.
2. rapid brain growth after birth
3. result of competing selective advantages for large brains and bipedalism.
|
|
birth patterns among fossil hominins
|
non-rotational until archaic Homo
|
|
human gestation length
|
...
|
ANTH 110: Exam 3